rick,
       for this particular plane, it is truly that easy to change inidence/decolage, not only for the wing but for the hor. stab as well. the flat plane of the wing's underside sits on top of the fuse sides secured typicaly with four nylon machine screws . the top of the sides are also the datum line. so, with no shims the line through the center of the the leading edge and trailing edge of the wing gives 1.5 degrees pos. incidence (in relation to the datum) which is supposed to be level in straight and level flight. similarily, the tail wing sits atop the vert stab, who's top is parallel to the datum, so getting a degree negative means simply trigging the offset and shimming the appropriate thickness under one of the two small machine screws that secure it to it's saddle.... and yes, the vert stab is built strong enough. built hollow foil  from 1/32" ply.  the foil is 3/8" at it's thickest point with a 1/8"thick by 3/4" wide ply platent epoxied on top for the saddle. the elevator linkage is by belcrank, up through the sta and a custom made control horn allows the entire assembly to be inside the vert. stab. all a change in incidence requires is the proper shim and a small linkage adjustment to return the elevator to neutral after shimming. so both surfaces are very easily adjustable.
      my concerns are whether i am correct in assuming that the incidence angle of the wing is defined by the line through the leading and trailing edge, in relation to the datum. i fairly well understand the whole theory of incidence angles and how decolage, the cg,  the stability margine and airspeed  work together (or against each other)  to stabilize the plane....very simar to the same elements, with different names of course on a sailboat. i just want to know if the line, as described, is the referance for incidence for my particular airfoil shape, namely, a semi-symetrical-flat bottom wing, just a line on a full symetrical is used when setting decolage.
     being sure of this one particular element  (the purpose of my question, initially) and all of this board's excellent advice, will allow me to continue, knowing that i have at least, got an initial decolage set up that should work.......you gotta start somewhere!